Inland and Near-Shore Water Profiles Derived from the High-Altitude Multiple Altimeter Beam Experimental Lidar (MABEL)

Abstract

The Advanced Topographic Laser Altimeter System (ATLAS) on the Ice, Cloud, and Land Elevation Satellite (ICESat-2) mission is a six beam, low energy, high repetition rate, 532 nm laser transmitter with photon counting detectors. Although designed primarily for detecting height changes in icecaps, sea ice and vegetation, the polar-orbital satellite will observe global surface water during its designed three year life span, including inland water bodies, coasts, and open oceans. In preparation for the mission, an ICESat-2 prototype or the Multiple Altimeter Beam Experimental Lidar (MABEL), was built and flown on high altitude aircraft experiments over a range of inland and near-shore targets. The purpose was to test the ATLAS concept and to provide a database for developing an algorithm that detects along track surface water height and light penetration under a range of atmospheric and water conditions. The current analysis examines the datasets of three MABEL transects observed from 20 km above ground of coastal and inland waters conducted in 2012 and 2013. Transects ranged from about 2 to 12 km in length and included the middle Chesapeake Bay, the near shore Atlantic coast at Virginia Beach, and Lake Mead. Results indicate MABEL's high capability for retrieving surface water height statistics with a mean height precision of approximately 5-7 cm per 100m segment length. Profiles of attenuated subsurface backscatter, characterized using a Signal to Background Ratio written in Log10 base, or LSBR 0 , were observed over a range of 1.3 to 9.3 meters depending on water clarity and atmospheric background. Results indicate that observable penetration depth, although primarily dependent on water properties, was greatest when solar background rate was low. Near shore bottom reflectance was detected only at the Lake Mead site down to maximum of 10 m under a

Analysis of MABEL Bathymetry in Keweenaw Bay and Implications for ICESat-2 ATLAS

“…Only one, small area was examined in this study, but a preliminary review of the suite of existing MABEL data reveals high-probability returns in other parts of Lake Superior, as well as a location along the Northern Icelandic coast. Additionally, Jasinski et al [52] noted MABEL bathymetry in Lake Meade. (These data were qualitatively assessed, but not included in the quantitative analysis of bathymetry in this study, due to a lack of available reference bathymetry for the sites.…”

“…MABEL has also been shown to detect bathymetry, in the low-turbidity waters of Lake Mead and depths of up to approximately one Secchi depth [52]. Focused primarily on the retrieval of water surface height statistics, Jasinski et al [52] includes a brief qualitative discussion of depth profiles observed in the photon-elevation data. However, the study did not account for index-of-refraction and vertical-datum corrections or include a quantitative comparison with existing bathymetry from dedicated bathymetric-mapping instruments.…”

The future of Earth observation in hydrology

“…SWOT will fill a major void in our observational capabilities. NASA's ICESat-2, while primarily focused on precise laser altimetry for ice sheet mapping, will also prove valuable for monitoring surface water elevations (Jasinski et al, 2016), particularly before the launch of SWOT. Other missions, such as NOAA's Suomi National Polar-orbiting Partnership (Suomi NPP; launched in 2011) Joint Polar Satellite System 1 (JPSS-1; scheduled for launch near the end of 2017), and future missions in the JPSS series are mainly geared towards atmospheric measurements, but all will carry Visible Infrared Imaging Radiometer Suite (VIIRS) instruments, which collect visible and infrared imagery useful for monitoring snow cover and vegetation as an input to retrieval algorithms for numerous hydrological variables.…”

Assimilation of Satellite Altimetry Data for Effective River Bathymetry

“…The error standard deviation ( σ o ) adopted for synthetic SWOT altimetry data is 10 cm, in accordance with Biancamaria et al () for a water surface area greater than 1 km 2 . ICESAT 2 errors are based on Jasinski et al (), who used an ICESAT 2 prototype called Multiple Altimeter Beam Experimental Lidar to assess the satellite data on inland waters, and have indicated average errors of 5 cm. The error adopted for JASON 3 is the same as JASON 2 ( σ o = 28 cm), and the SARAL/AltiKa error is 17.5 cm, as estimated by Schwatke et al () for the Amazon basin.…”